Analysis on the effects of energization mode for magnetically controlled shunt reactor

Generally, Magnetically Controlled Shunt Reactor (MCSR) energized without pre-excitation, which is called direct energization, may result in overvoltage problem on the dc bus of the MCSR and harmonic problem to the network. Based on the analysis of the current characteristics for the control winding of MCSR under steady-state operation, a novel energization method with dc pre-excitation in the control winding of MCSR is proposed in this paper. By analyzing the operating point for each MCSR core during energization, the cause of the overvoltage on the dc bus after direct energization is investigated. Furthermore, this paper discusses the effects of energization with and without pre-excitation on MCSR and the network. Theoretical analysis, simulation results and experimental tests have demonstrated the capability of pre-excited energization in mitigating the overvoltage and harmonic problems caused by direct energization.